A number of applications in the construction or repair of solid articles involve the selective removal of material from a bulk in order to produce a desired conformation or shape. For example a builder may remove some wood from a beam in order to produce a neat fit--more likely if the house being built is non-rectangular; a foundry removes surplus metal from sprues or joints between mould parts when producing a casting; a wood carver selectively removes wood in order to produce a carving a panel beater frequently removes surplus plastic filler which was placed within a defect in an automotive panel to build it tip, so that the outline conforms with the original outline of the panel; or a boat builder may have to remove kilograms of material, such as lead-filled fibreglass when shaping or repairing a hull.
In a previous Application published as WO 95/29788 on Nov. 9, 1995, Applicant described an invention in which a first aspect comprised an accessory for a grinder including a rotatable tool having a shape substantially that of a disk, having an axis of rotation and capable of being mounted on an arbor of an angle grinder, characterised in that the rotatable tool is provided with a working zone extending inwardly from the perimeter of the tool; and rest means extending substantially inwardly from the working zone of the tool, which rest means is displaced from the working zone along the line of the axis of rotation.
For clarity it should be understood that the term "working zone" refers to the permitted location on the tool where cutting or abrading means might be located. The "working surface" of the tool refers to those parts of the working zone where cutting or abrading means are actually located.
In a preferred aspect of the previous Aplication the rest means is concentric with and supported on the rotatable tool, and most preferably comprises a portion of a convex surface
In an alternative embodiment the previous Application comprises an accessory for a grinder characterised in that the rest means comprises a fixed rubbing surface or nose supported on the angle grinder and displaced so as to be supported beyond the rotatable tool. (By "beyond" we mean beyond the end of the arbor, or below the tool as it is normally held).
In a further preferred aspect the previous Application comprises a rotatable disk-shaped accessory for a grinder having a working zone and a rest means, characterised in that the working zone extends inwardly over the surface of the disk from the perimeter over from about a first third to about two thirds of the radius.
Other preferred featured of the previous Application include providing that: the working surface of the rotatable tool with at least one cutting tooth; each cutting tooth has at least one cutting edge lying in a plane substantially coplanar with the radially adjacent surface of the tool; and each cutting tooth projects from the radially adjacent surface of the tool by a height of up to 3 percent of the diameter, so that the depth of cut of each tooth is limited. Each cutting tooth can be additionally provided with a tooth rubbing surface or gauge surface; the rubbing surface projecting outwardly at least as far as the cutting zone of the tooth, thereby limiting the depth of cut of each tooth.
The accessories of the present invention are distinguished from those described in UK Patent Application 2 207 626 which teaches a metallic abrading disk with a recessed central portion and U.S. Pat. No. 4,835,912 which provides a species of flap disk with a rotatable central disk and, attached around and projecting beyond the periphery thereof, a plurality of sandpaper loops providing the abrasive element of the tool.